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In this paper, we consider Large Eddy Simulations (LES) for human stenotic carotids in presence of atheromasic plaque. It is well known that in such a pathological condition, transitional effects to turbulence may occur, with relevant clinical implications such as plaque rupture. The first aim of this work is to provide a way to define a Direct Numerical Simulation (DNS). In our context turbulence is not statistically homogeneous isotropic and stationary. We define mesh size and time step by considering the reduced model of a 2D shear layer. Then, we compare the performance of LES ¾ model (both static and dynamic) and of mixed LES models (where also a similarity model is considered) with that of DNS in a realistic scenario of a carotid. The results highlight the effectiveness of the LES ¾ models in terms of accuracy, especially for the static model.

In this paper, we consider large eddy simulations (LES) for human stenotic carotids in presence of atheromasic plaque, a pathological condition where transitional effects to turbulence may occur, with relevant clinical implications such as plaque rupture. We provide a reference numerical solution obtained at high resolution without any subgrid scale model, to be used to assess the accuracy of LES simulations. In the context we are considering, ie, hemodynamics, we cannot refer to a statistically homogeneous, isotropic, and stationary turbulent regime; hence, the classical Kolmogorov theory cannot be used. For this reason, a mesh size and a time step are deemed fine enough if they allow to capture all the features of the velocity field in the shear layers developed after the bifurcation. To assess these requirements, we consider a simplified model of the evolution of a 2D shear layer, a relevant process in the formation of transitional effects in our case. Then, we compare the results of LES sigma model (both static and dynamic) and mixed LES models (where also a similarity contribution is considered). In particular, we consider a realistic scenario of a human carotid, and we use the reference solution as gold standard. The results highlight the accuracy of the LES sigma models, especially for the static model.